Alaska Extended Forecast Discussion NWS Weather Prediction Center College Park MD 709 PM EDT Wed Aug 11 2021 Valid 12Z Sun Aug 15 2021 - 12Z Thu Aug 19 2021 ...Overview... An upper low will remain/meander in the Arctic/Beaufort through next week with systems moving eastward underneath its circulation across northern areas. Additional troughing will reload near the Aleutians into the Gulf to the north of building upper ridging in the mid-latitudes. This keeps a quasi-zonal flow across much of the mainland into the Panhandle with several systems and rainfall episodes. ...Guidance/Predictability Evaluation... The ensembles remained in good agreement overall with some expected timing/amplitude differences next week over the Bering and near the Aleutians as a couple more systems enter the picture. Overall, a blended solution was preferred. This included the 12Z ECMWF which paired best with the ensembles, followed by the 12Z GFS and Canadian. The UKMET was again farthest from the consensus. The lead systems south of the Aleutians Saturday, containing the remnant moisture of ex-Tropical Storms Lupit and Mirinae, will tend to lift northeastward toward the central/eastern Aleutians and AKPen next week, bringing in some rainfall to the region. The system will move into the Gulf around late next Tue with a middle ground solution showing little change from the forecast 24 hrs ago. ...Weather/Threats Highlights... Over northwestern areas, deep upper low in the Arctic will allow a northern stream system out of Russia to push eastward underneath/around its circulation. This will bring in an expanding area of precipitation to the northwestern corner of the state and across the Brooks Range early next week as the boundary slowly sinks southward and then eastward just ahead of the upper trough. Some rainfall could be locally modest to heavy over the Seward Peninsula eastward to the Koyukuk and Yukon River Valleys. By later next week, system will move through the Gulf bringing another round of rain for the Panhandle. Temperatures will generally be below normal across most of the state, focused on northern areas under the trough. Some slow moderation is possible later next week but the continued troughing will likely result in only small changes to the pattern, perhaps nearing or above normal temperature across the Aleutians by next Wednesday/Thursday. Fracasso Additional 3-7 Day Hazard Information can be found on the WPC medium range hazards outlook chart at: https://www.wpc.ncep.noaa.gov/threats/threats.php Hazards: - Heavy rain across portions of mainland Alaska, Sun-Mon, Aug 15-Aug 16. - Heavy rain across portions of the Alaska Panhandle and mainland Alaska, Tue-Wed, Aug 17-Aug 18. WPC medium range Alaskan products including 500mb, surface fronts/pressures progs and sensible weather grids can also be found at: https://www.wpc.ncep.noaa.gov/alaska/ak_5dayfcst500_wbg.gif https://www.wpc.ncep.noaa.gov/alaska/akmedr.shtml https://www.wpc.ncep.noaa.gov/alaska/ak_5km_gridsbody.html